Joanna Stanley,1 Karolina Sulek,1 Christine Jasoni,2 David Broadhurst,2 Irene Andersson,2 Wen Hong,4 Sandra Davidge,4 Louise Kenny,6 Colin Sibley,7 Rupasri Mandal,8 David Wishart8 and Phil Baker1
1 Liggins Institute, , Auckland; 2 Department of Anatomy, University of Otago, Dunedin; 3 Department of Medicine, University of Alberta, Edmonton, Canada; 4 Department of Obstetrics & Gynecology, Zhejiang University, Hangzhou, Zhejiang. Province, China; 5 Departments of Obstetrics & Gynecology/Physiology, University of Alberta, Edmonton; Canada; 6 Anu Research Centre, University College Cork, Cork, Ireland; 7 Maternal & Fetal Health Research Centre, University of Manchester, Manchester, UK; 8 TMIC, University of Alberta, Edmonton, Canada
Background: Fetal growth restriction (FGR) is associated with long-term health consequences in adults, including obesity, which may be linked to perturbations in neuronal development and the expression of receptors involved in appetite/body weight regulation. Hypothalamic neuropeptide Y (NPY)-containing neurons stimulate food intake and decrease energy expenditure. We hypothesized that maternal treatment with sildenafil during pregnancy would normalise the development of NPY-containing neurons in offspring. Via metabolomic profiling, we looked for mechanism(s) of action responsible for the sildenafil-induced rescue of fetal growth via aberration of the maternal metabolic profile.
Method: Catechol-O-methyltransferase knockout mice (COMT-/-), a model of FGR, and wild type C57BL6/J mice received sildenafil (0.2 mg/ml) or placebo from gestational day 12.5-18.5. On day 18.5, dams were sacrificed, brains from the pups were removed and maternal blood samples were collected. NPY fibers were imaged using immunohistochemistry, followed by confocal microscopy. The paraventricular nucleus (PVN) was identified, and average pixel intensity was analysed using ImageJ. We applied a targeted quantitative metabolomics approach using a combination of DI-MS with a reverse-phase LC-MS/MS on ABI 4000 Q-Trap MS for the maternal plasma samples.
Results: There was a significant effect of sildenafil treatment on NPY fiber density (p<0.001) in the PVN across treatment groups. Fiber density was significantly increased in both C57BL/6J (p<0.01) and COMT-/- (p<0.05) pups from treated mothers. Sildenafil treatment reversed 13 out of 18 altered metabolites from the acylcarnitines, glycerophospholipids, sphingolipids and bigenic amines class in the COMT-/- dams.
Conclusion: Increased NPY release in the PVN results in increased food intake, as well as increased energy storage in the form of fat. Given that sildenafil treatment increased pup birth weight, NPY-mediated increases in fat storage may be one mechanism by which this was achieved. Sildenafil treatment was able to significantly restore the metabolic balance, improving fetal development.